Tectonostratigraphy of the Merida Massif reveals a new Cadomian suture zone exposure in Gondwana (SW Iberia)

Neoproterozoic and Palaeozoic rocks of the Merida Massif (SW Iberia) have been grouped into tectonostratigraphic units. Each unit is separated from the rest ones by either crustal-scale thrusts and/or extensional detachments. The lowermost unit (Magdalena Gneisses; lower plate) has continental crust affinity, and rest below a mafic-ultramafic ensemble, referred to as the Merida Ophiolite (suture zone). The Serie Negra Group constitutes a unit with continental crust affinity (Upper Schist-Metagranitoid Unit; upper plate) located on top of the Merida Ophiolite. A carbonate-rich succession (Carija Unit) occupies the uppermost structural position. Structural and previous isotopic data suggest that this suture zone was formed during the Cadomian Orogeny. Superimposed shortening during the late Palaeozoic formed upright to NE-verging folds and thrusts that affected this suture zone and juxtaposed it onto Ordovician strata during the Variscan Orogeny. The Merida Ophiolite represents a new Cadomian suture zone exposure in the Gondwanan realm of the Iberian Massif, but its root zone is yet to be identified. This ophiolite shares a far-travelled nature with other Cadomian and Variscan suture zone exposures in Iberia, making the latter a piece of lithosphere built through inland transference of allochthonous terranes from peri-Gondwana onto mainland Gondwana during the Neoproterozoic-Cambrian and the Devonian-Carboniferous periods.

Automated summary

The Neoproterozoic and Palaeozoic rocks of the Merida Massif in SW Iberia have been grouped into tectonostratigraphic units, separated by crustal-scale thrusts and/or extensional detachments. This tectonic setting was formed during the Cadomian Orogeny and later modified by the Variscan Orogeny, resulting in the juxtaposition of different units and the formation of folds and thrusts. The Merida Ophiolite represents a Cadomian suture zone exposure in the Gondwanan realm, reflecting inland transference of allochthonous terranes onto mainland Gondwana during different geological periods.